A number of systems are disclosed in the prior art for directing a moving web to a predetermined location such as into threading engagement with rolls forming a nip or the like. Examples of such systems are those disclosed in U.S. Pat. Nos. 3,999,696 and 4,014,487 wherein a gas such as air is directed through a restricted opening under pressure whereupon it attaches itself to a flow attachment surface due to the "Coanda effect", is directed to the predetermined location and entrains ambient air. The web is placed into the path of the moving gas and entrained thereby. The gas is moving at a velocity greater than the velocity of the moving web and thus the web is straightened out and directed to the predetermined location.
While the arrangements illustrated in the aforesaid patents are suitable for use in the vast majority of operational environments, reel threading presents entirely different problems than the usual situation where a web is delivered from a dryer roll or the like and guided into a predetermined location essentially in line with the threading system. The problem of reel threading becomes particularly aggravated when a break has occurred and it is desired to rethread the reel spool. In such a situation, not only is the reel spool location in opposition to the point on the reel drum where threading is initiated, but the threading of the spool must often be accomplished through a restricted space formed by the reel drum and another reel spool placed in standby or pre-windup position. Thus, not only must the threaded web pass around the curved surface of the reel drum, it must pass through a restricted opening while doing so. In the past, two principal approaches have been applied in the art of reel threading. The first calls for the utilization of ropes which pass about the periphery of the reel drum near the edge thereof. The operator, when threading, places the web in the rope nip which, in theory at least, results in the web being carried about the periphery of the drum to the location of the spool to be threaded. This procedure is, however, quite dangerous since the tensioned rope can break and additionally the operator can get his hand caught when initially inserting the web in the rope nip.
The other primary prior art approach has been to employ a series of air jet nozzles, often hand-held, about the periphery of the reel drum. Through manipulation of the air jets an attempt is made to keep the web on the reel drum until it reaches the vicinity of the spool. This air blast technique is quite unsatisfactory since it often calls for several people to aim the air at the web at various locations in an attempt to keep the web in a desired path of movement. What often results, however, is essentially uncontrolled web movement, especially lateral movement, and a great deal of time frequently goes by before the web is finally directed to the vicinity of the reel spool. The use of conventional air nozzles to effect reel threading becomes an especially difficult task when lighter weight paper grades, such as tissue, are to be threaded since these lighter grades, unless kept under tension at all times, tend to bunch up and jam at any restricted openings through which the web must pass.
In addition to the aforedescribed rope threading and air blast threading techniques, it is not uncommon for operators to attempt to thread slower machines through guidance of the web by hand about the periphery of the reel drum. Needless to say, this practice is highly undesirable and can easily result in injury to the person or persons attempting hand threading.
The present invention provides a system of relatively inexpensive and simple construction which utilizes the phenomenon known as the "Coanda effect" to entrain a moving web of flexible material and quickly direct same along the curved surface of a reel drum to the vicinity of a cooperating reel spool about which the web is to be wound without the necessity of manual manipulation.